The field of the invention is that of heated hand grips generally, and in particular, heated hand grips for motorcycles, snow mobiles, and other vehicles having a source of power and intended for use in cold weather in the out-of-doors.
When users operate motorcycles or snowmobiles in cold weather, their hands get cold, even with warm clothing. The heat transfer from a limb extension like a foot or a hand makes it very difficult to keep warm. It is important that a person operating such a vehicle concentrate on driving, rather than on physical needs. If the hands become too cold, they can become numb, and the person may not be able to operate the vehicle. In a worst case, frostbite or other injury could result from prolonged exposure. As a result, heated hand grips have been used for such vehicles.
There are problems with the heated hand grips that have been used to date. For example, in U.S. Pat. No. 4,471,209, an early invention, uses a grip heater with an electrical heating element comprising a resistive wire wrapped over a tubular insulator with a pair of helical recesses in which the heating element resides. A soft, grippable rubber outer surface then covers the wire. However, early control systems, such as those in this patent, offered only “low” and “high” settings, which was provided by two different heating elements. These early heaters, however, tended to suffer one or more breaks in the resistive wire used for the heating, and thus were not satisfactory.
Another grip heater is depicted in U.S. Pat. No. 7,010,997. This patent discloses a heating grip for the right-side handle bar, that is, the throttle grip. The heater requires separate cables and connectors to the vehicle battery or other power source. After entering the motorcycle grip, the heating coils form a large spiral transverse to the axis of the handle bar. As the user rotates the throttle grip backward or forward, the spiral will provide slack to prevent stressing the connecting end of the heater wire. While providing a heater to the right-side handle bar, this solution will also require an equal number of wires and connectors for the left hand grip. In addition, no control system is mentioned for controlling the temperature of the grips and preventing thermal runaway.
Another effort is shown in U.S. Pat. No. 7,091,450, which again features two different heating elements, this time placed into helical recesses in a tubular support for the hand grips. Whatever its supposed improvement in reliability, this grip heater has high costs, resulting from the extensive preparation of tubular supports with their helical grooves. In addition, cross-over points for the heating elements are preferably isolated electrically from one another, requiring small insulating pads and the labor to install the pads and place the wires so that they do not contact each other. Instead of the small pads, the tubular support may instead use small crossover protrusions, similar to wire grips, to insure that the crossing wires will not touch each other. These cross-over points will eventually become stress-risers for the wire, which will strain and eventually break at some of the cross-over points.
Still another example is seen in U.S. Pat. No. 7,214,906. This patent discloses a very complicated control system for independent control of both left and right hand grips. The system is sufficiently complicated that it requires a microprocessor controller and a memory. The microprocessor requires a control panel and is equipped with flashing LEDs, up and down buttons, and individual left and right buttons. The control panel must be placed somewhere accessible to the user, adding to the clutter on the motorcycle controls. The control system is very complicated, but does not provide for closed-loop thermal compensation of the grip temperature. The patent provides few details of the actual heated hand grips themselves. At a minimum, this system disclosed will not help manufacturers of motorcycles or heated hand grips control costs.
What is needed is a less complicated, more reliable heating grip for cold weather, outdoor vehicle, such as motorcycles or snowmobiles.